The Collaborative International Dictionary of English v.0.48:

Flippant \Flip"pant\, a. [Prov. E. flip to move nimbly; cf. W.
   llipa soft, limber, pliant, or Icel. fleipa to babble,
   prattle. Cf. Flip, Fillip, Flap, Flipper.]
   1. Of smooth, fluent, and rapid speech; speaking with ease
      and rapidity; having a voluble tongue; talkative.
      [1913 Webster]

            It becometh good men, in such cases, to be flippant
            and free in their speech.             --Barrow.
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   2. Speaking fluently and confidently, without knowledge or
      consideration; empty; trifling; inconsiderate; pert;
      petulant. "Flippant epilogues." --Thomson.
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            To put flippant scorn to the blush.   --I. Taylor.
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            A sort of flippant, vain discourse.   --Burke.
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The Collaborative International Dictionary of English v.0.48:

Flippant \Flip"pant\, n.
   A flippant person. [R.] --Tennyson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flippant
    adj 1: showing inappropriate levity [syn: flippant, light-
           minded]